Two-sided tapes and hot-melt type adhesives are used as adhesives for temporary fixation of optical lenses, prisms, arrays, silicon wafers, semiconductor packaging parts, and so on, and members bonded or laminated with use of these adhesives are cut into a predetermined shape, followed by removal of the adhesive to produce processed members. With respect to the semiconductor packaging parts, for example, they are fixed on a substrate with a two-sided tape and then cut into desired parts, and the two-sided tape is irradiated with ultraviolet rays to be separated from the parts. Furthermore, in the case of the hot-melt type adhesive, members are bonded therewith and heated to let the adhesive penetrate into their interspace, and then the members are cut into desired parts, followed by removal of the adhesive in an organic solvent.
However, in the case of the two-sided tape, there were problems that it was difficult to achieve satisfactory thickness accuracy; its adhesive strength was weak, so that in processing the parts, chipping of the parts was likely to occur (i.e. inferior in the chipping property); that it was impossible to separate the tape without heating at 100° C. or more; and that, where it was separated by irradiation with ultraviolet rays, it was impossible to separate the tape if an adherend had a poor UV transmittance.
In the case of the hot-melt type adhesive, it could not be effective in bonding without heating at 100° C. or more, so that there was a restriction on the members to be used. Furthermore, it was necessary to use an organic solvent in removal of the adhesive, and washing steps with an alkali solvent and a halogen type organic solvent were cumbersome and also problematic from the viewpoint of working environments.
In order to overcome these drawbacks, photocurable or heat-curable adhesives for temporary fixation were proposed which contain a water-soluble compound such as a water-soluble vinyl monomer. These adhesive compositions solved the problem of the removability in water, but they still had problems that the adhesive strength was low in fixation of parts and that the members after being cut had poor dimensional accuracy. Furthermore, adhesives for temporary fixation were proposed which had adhesion improved with use of a specific, highly hydrophilic (meth)acrylate, and also had removability improved by swelling and partial dissolution. However, a cutting process involves generation of frictional heat between the parts and a cutting jig such as a blade or a diamond cutter and thus is carried out while cooling the parts with a large amount of water. Therefore, a cured resin of the above highly hydrophilic composition swells to become soft during the cutting, whereby higher dimensional accuracy cannot be achieved. In addition, the cured resin dissolved in part remains as a residual adhesive on the members after the removal, which causes a problem in appearance.
In addition, in the case of photocurable adhesives, there is a problem that the material for members to be processed is limited to a material which transmits light such as ultraviolet light, and a material not transmitting light, such as a ceramic material, a colored plastic material or the like, can not be used. Further, heat-curable adhesives such as epoxy resins require a heating apparatus in many cases and thus have a problem such that it takes time for curing, and further labor saving, energy saving and shortening of the working time are required. (cf. Patent Documents 1, 2 and 3).    Patent Document 1: JP-A-06-116534    Patent Document 2: JP-A-11-71553    Patent Document 3: JP-A-2001-226641